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Numerical Study of Atrial Fibrillation Effects on Flow Distribution in Aortic Circulation
Amin Deyranlou1, Josephine H Naish2, Christopher A Miller3,4,5
1Department of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, Manchester, M13 9PL, UK.
Insights
Atrial fibrillation (AF) can alter blood flow, potentially increasing stroke risk. This study quantifies how AF traits affect aortic flow, revealing areas prone to clot formation and atherogenesis.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Computational Fluid Dynamics
Background:
- Atrial fibrillation (AF) is a common arrhythmia impacting cardiac function and potentially leading to stroke.
- The precise mechanisms and origins of thromboembolism in AF patients remain debated.
- Alternative hypotheses suggest thrombus formation in the aorta or carotid arteries.
Purpose of the Study:
- To investigate the impact of common atrial fibrillation (AF) traits on aortic blood flow dynamics.
- To quantify the sensitivity of aortic flow to specific AF-related conditions.
- To explore the potential for atherogenesis and thrombus formation in the aorta due to AF.
Main Methods:
- Coupled in-house codes with ANSYS-CFX for computational fluid dynamics (CFD) simulations.
- Parametric study analyzing four AF traits: lack of atrial kick, atrial remodeling, left ventricle systolic dysfunction, and high-frequency fibrillation.
- Quantification of aortic flow rate and flow structures.
Main Results:
- AF traits significantly reduce flow rate at the left ventricular outflow tract.
- Reduced flow impacts systemic, cerebral, and coronary blood perfusion.
- Increased endothelial cell activation potential (ECAP) and altered flow patterns were observed.
- Predisposed regions for atherogenesis and thrombus formation identified in the ascending aorta, aortic arch, and descending thoracic aorta.
Conclusions:
- Atrial fibrillation significantly alters aortic hemodynamics, reducing overall blood perfusion.
- AF-induced flow changes create conditions conducive to atherogenesis and thrombus formation within the aorta.
- Findings contribute to understanding AF-related stroke risk beyond intra-atrial clot formation.
Abstract:
Atrial fibrillation (AF) is the most common type of arrhythmia, which undermines cardiac function. Atrial fibrillation is a multi-facet malady and it may occur as a result of other diseases or it may trigger other problems. One of the main complications of AF is stroke due to the possibility of clot formation inside the atrium. However, the possibility of stroke occurrence due to the AF and the location from which an embolus dispatches are subject of debate. Another hypothesis about the embolus formation during AF is thrombus formation in aorta and carotid arteries, embolus detachment and its movement. To investigate the possibility of the latter postulation, the current work suggests a parametric study to quantify the sensitivity of aortic flow to four common AF traits including lack of atrial kick, atrial remodelling, left ventricle systolic dysfunction, and high frequency fibrillation. The simulation was carried out by coupling several in-house codes and ANSYS-CFX module. The results reveal that AF traits lower flow rate at left ventricular outflow tract, which in general lowers blood perfusion to systemic, cerebral and coronary circulations. Consequently, it leads to endothelial cell activation potential (ECAP) increase and variation of flow structure that both suggest predisposed areas to atherogenesis and thrombus formation in different regions in ascending aorta, aortic arch and descending thoracic aorta.
